1. Field of the Invention
This invention relates to an electrocardiographic current derivation electrode and, more particularly, to an electrocardiographic current derivation electrode for deriving minute current generated in a man in a state secured to the skin of the man.
2. Prior Art
As is well known in the art, electricity is induced in a man by the activities of the heart, brain, muscles, etc.
Particularly, electricity generated in the heart is recorded by an externally provided electrocardiograph as minute voltage induced at the man's skin for effecting diagnosis of the heart. To this end, an input section of the electrocardiograph is electrically coupled to the man. This means that it is necessary to have electrodcardiographic current derivation electrodes in close contact with the man's skin.
A prior art electrocardiographic electrode to be held in close contact with the man's skin will now be described with reference to FIGS. 5 to 7. FIG. 5 is a perspective view of the electrocardiographic electrode 1. The electrode 1 has a substantially circular sticky base 16. The sticky base is a doughnutlike woven cloth having a central opening 17. Its back side has stickiness to be held in close contact with the skin M of a man, as shown in FIG. 7.
An electrode holder 18 made of a hard synthetic resin is bonded to the top side of the sticky base 16 such as to close the opening 17. The electrode holder has a magnetic lead coupler 19 projecting from the top side.
To the underside of the lead coupler 19 is secured an electrode 20, as shown in FIG. 7, for deriving minute current from the heart in direct contact with the skin M of the man.
FIG. 6 shows the back side of a lead connector 21 for leading the minute current in the heart derived from the electrode 20 through the lead 4 to an electrocardiograph (not shown). The lead connector 21 is made of a hard resin and has substantially the same size as the electrocardiographic current derivation electrode 1. The lead connector 21 has a recess 22. An electromagnetic electrode coupler 23 is received in the recess 22 and secured to the lead connector 21. The electrode coupler 23 is connected through a lead 4 to an electrocardiograph (not shown).
For recording an electrocardiogram using the electrocardiographic current derivation electrode 1 having the above construction, cream is preliminarily applied to the skin M of a man to reduce the electric resistance. Then, the sticky base 16 of the electrocardiographic current derivation electrode 1 is bonded to the cream-applied skin M. Subsequently, the magnetic electrode coupler 23 of the lead connector 21 is bonded to the lead coupler 19 of the electrocardiographic current derivation electrode 1, thus coupling the lead connector 21 to the electrocardiographic current derivation electrode 1. In this state, minute voltage derived from the heart by the electrode 20 is supplied through the lead 4 to an electrocardiograph (not shown) for recording.
In the prior art arrangement as described above, magnets are used on both the lead side and the electrode side. Therefore, the arrangement is heavy, and also the structure for supporting the magnets is complicated and large in size, and also it feels hard. For these reasons, the arrangement is unsatisfactory as a tool to be attached to the man's skin, and the cost of manufacture is expensive.